XArray: Add xa_store_bh() and xa_store_irq()

These convenience wrappers disable interrupts while taking the spinlock.
A number of drivers would otherwise have to open-code these functions.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

Documentation/core-api/xarray.rst

@@ -167,6 +167,8 @@ Takes RCU read lock:
 
 Takes xa_lock internally:
  * :c:func:`xa_store`
+ * :c:func:`xa_store_bh`
+ * :c:func:`xa_store_irq`
  * :c:func:`xa_insert`
  * :c:func:`xa_erase`
  * :c:func:`xa_erase_bh`
@@ -247,7 +249,8 @@ Sharing the XArray with interrupt context is also possible, either
 using :c:func:`xa_lock_irqsave` in both the interrupt handler and process
 context, or :c:func:`xa_lock_irq` in process context and :c:func:`xa_lock`
 in the interrupt handler.  Some of the more common patterns have helper
-functions such as :c:func:`xa_erase_bh` and :c:func:`xa_erase_irq`.
+functions such as :c:func:`xa_store_bh`, :c:func:`xa_store_irq`,
+:c:func:`xa_erase_bh` and :c:func:`xa_erase_irq`.
 
 Sometimes you need to protect access to the XArray with a mutex because
 that lock sits above another mutex in the locking hierarchy.  That does